The present invention relates to a locking-type differential gear mechanism, and in particular relates to an actuator mechanism for actuating the lockup of a differential mechanism.
Locking differential mechanisms are well known. Such differentials are known to be used as interaxle differentials such as in a four-wheel drive, as well as inter-wheel differentials interposed between the wheels on a common axle. The locking-type of differential mechanisms which are knwon in the art normally include a mechanism for locking two rotatable parts of the differential together. The specific locking mechanism may, and has in the art, taken many different forms and generally is a clutch mechanism, such as a disc pack, cone clutch, etc. The known locking-type differential mechanisms also include an actuator or engagement mechanism for actuating the locking mechanism (clutch) to effect the lockup of the two differential parts.
Ottemann U.S. Pat. No. 3,606,803 discloses a typical known locking-type differential in which the side gear of the differential is locked through a suitable clutch mechanism to the case of the differential upon a predetermined degree of differential action. When the differentiating action reaches a predetermined degree, an actuator mechanism is operated which actuates the clutch mechanism to effect the lockup, and specifically lock the side gear of the differential to the differential casing. In U.S. Pat. No. 3,606,803, for example, the clutch mechanism is actuated upon relative rotation of the side gear and a cam member. The cam member is retarded from rotation with the side gear by operation of the actuating mechanism for the differential. The actuator mechanism comprises a series of weights which are thrown out upon a predetermined amount of differential action occurring and when thrown out are latched from rotating, and accordingly effect a retarding action on the cam member which in turn results in the side gear rotating relative to the cam, which then actuates the clutch mechanism for locking the side gear to the case of the differential. In the Ottomann U.S. Pat. No. 3,606,803, the actuator mechanism is mounted on the differential case and may be actuated to cause engagement of the clutch to lock the differential due to case centrifugal force as opposed to merely differentiating action occurring. Also, the actuator mechanism, which includes weights, which are thrown out and then latched, is subject to the problem of the possibility of the weights missing and not being latched. In addition, such actuator mechanisms are somewhat complicated and involve a number of parts, and therefore are not as reliable as may be possible.